1. Field of the Invention
The present invention relates, in general, to weight detecting devices for microwave ovens and, more particularly, to a weight detecting device for microwave ovens which is used to detect a weight of food placed on an exterior casing of a microwave oven.
2. Description of the Related Art
FIG. 1 is a side sectional view of a microwave oven having a conventional weight detecting device.
As illustrated in FIG. 1, a microwave oven includes an interior casing 1 and an exterior casing 3. A guide plate 4 having a shelf shape is provided in a space defined between a top plate 2 of the interior casing 1 and the exterior casing 3. In the microwave oven of FIG. 1, the guide plate 4 is spaced apart from the top plate 2 of the interior casing 1 by a predetermined height, thus preventing heat from being transmitted from the interior casing 1 through the top plate 2 of the interior casing 1 to the guide plate 4. A weight sensor 5 is provided at a center of the guide plate 4.
In a conventional weight detecting device, the weight sensor 5 has a form of a piezoelectric element which is sensitive to a variation in temperature. Thus, to minimize a heat conduction from the interior casing 1 to the guide plate 4, the guide plate 4 is spaced apart from the top plate 2 of the interior casing 1 by a predetermined height and to surround the weight sensor 5.
However, the conventional weight detecting device has a problem that the guide plate 4 thereof surrounds the weight sensor 5, so a space to install the weight sensor 5 is increased and the size of the guide plate 4 is undesirably increased.
The conventional weight detecting device has another problem that the weight sensor 5 thereof has the form of the piezoelectric element, so a gap between the guide plate 4 and the top plate 2 of the interior casing 1 must be increased so as to minimize the heat conduction from the interior casing 1 to the guide plate 4, thus increasing a space to install the weight sensor 5.